Study the usefulness of in vitro sensitization of lymphoid cells with both syngeneic and allogeneic leukemia cells for immunotherapy of mouse leukemia. The conditions of in vitro sensitization will be extensively studied and the results will be evaluated by both in vitro and in vivo assays. While the in vivo assays may include some prophylaxis experiments, the emphasis will be on the study of the therapeutic effectiveness of the sensitized lymphocytes. Such therapeutic studies may include combinations of immunotherapy with other therapeutic modalities such as radiotherapy and chemotherapy.